IT公司100题-11-求二叉树中节点的最大距离

问题描述：

写程序，求一棵二叉树中相距最远的两个节点之间的距离。

10
/    
6      14
/     /  
4    8 12    16

分析：

二叉树中最远的两个节点，要么是根和一个叶子节点，要么是两个叶子节点。

 

代码实现：

// 11.cc
#include <iostream>
using namespace std;

typedef struct BSTreeNode {
    int data;
    BSTreeNode *left;
    BSTreeNode *right;
} tree_node;

// 创建二元查找树
void add_BSTree_node(tree_node* &p_current, int data) {
    if (NULL == p_current) {
        tree_node *node = new tree_node();
        node->left = NULL;
        node->right = NULL;
        node->data = data;
        p_current = node;
    } else {
        if (p_current->data > data)
            add_BSTree_node(p_current->left, data);
        else if (p_current->data < data)
            add_BSTree_node(p_current->right, data);
        else
            cout << "The data has already in the tree.";
    }
}

int helper(tree_node* root, int& depth) {
    if (!root) {
        depth = 0;
        return 0;
    }
    int ld, rd;
    int max_left = helper(root->left, ld);
    int max_right = helper(root->right, rd);
    depth = max(ld, rd) + 1;
    return max(max_left, max(max_right, ld + rd));
}

// 查找最大距离
int max_distance(tree_node* root) {
    int depth;
    return helper(root, depth);
}

int main() {
    tree_node *root = NULL;
    add_BSTree_node(root, 10);
    add_BSTree_node(root, 2);
    add_BSTree_node(root, 4);
    add_BSTree_node(root, 6);
    add_BSTree_node(root, 8);
    add_BSTree_node(root, 12);
    add_BSTree_node(root, 14);
    add_BSTree_node(root, 16);

    int depth;
    int max_d = max_distance(root);
    cout << max_d << endl;
}